Fuel supply pump for prime movers



Oct. 25, 1960 Filed March 17, 1954 F. c. MOCK 2,957,421

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Oct. '25, 1960 F. c. MOCK 2,957,421

. FUEL SUPPLY PUMP FOR PRIME MOVERS Filed March 17, I954 6 Sheets-Sheet4 INVENTOR. FIPA/VA/KT/VUC'K ATTOAA/flf FUEL SUPPLY PUMP FOR PRIMEMOVERS Filed March 17, 1954 6 Sheets-Sheet 5 INVENTOR.

a FRANK (War/r United States Patent 2,957,421 FUEL SUPPLY PUMP FORPRINIE MOVERS Frank C. Mock, South Bend, Ind., assignor to The BendixCorporation, a corporation of Delaware Filed Mar. 17, 1954, Ser. No.416,750

14 Claims. (Cl. 103-38) covering a Fuel Supply Pump for Prime Movers,which application will now be permitted to lapse in view of its beingsuperceded by the present application.

This invention relates to fuel pumps of the variable displacement,reciprocating plunger swash plate type for pressurizing fuel to primemovers, especially gas turbine engines for aircraft, and adapted torespond automatically to a change in pressure requirements. Certaintypes of engines, notably turbojet engines for aircraft, may requireextremely high delivery pressures at the burner discharge nozzles toobtain good fuel atomization and efiicient combustion, and the nozzlepressure requirements may vary over a wide range between operation atsea level and high altitudes. The reciprocating plunger, swash platetype of pump is well adapted to supply fuel at high pressures, butautomatic regulation or variation of pump delivery in relation to enginefuel requirements poses quite a problem, and an object of the presentinvention is to provide in a pump of the type specified self-contained,reliable, regulator mechanism which acts to vary the angle of the swashplate as a function of pump discharge pressure and engine speed.

Another object is to provide in a pump of the type specified regulatormechanism which may be readily adapted to deliver fuel at pressuresconforming todifferent engine requirements.

Another object is to provide in a pump of the type.

specified regulator mechanism operative to control the pumping stroke insuch a manner that sufficient discharge pressure is maintained for therequired fuel delivery under all operating conditions and said pressureis also automatically maintained within safe limits so as to maximizethe operating life of the pump.

A further and more specific object is to provide regulator mechanism fora swash or wobble plate type of fuel pump embodying means forinterposing a resilient force on the plate tending to push the plate tomaximum stroke position against the resistance of plunger returnsprings, which mechanism may be arranged so that such force will remainsubstantially constant throughout the different pitch positions of saidplate, or will vary according to any desired predetermined schedule.

Another object of this invention is to provide regulator mechanism for aswash or wobble plate type of fuel pump embodying means for producing aresultant of mechanical moments about the pivot or trunnion of the swashplate at any given pump speed which varies in such a way that pumpdischarge pressure follows, or is a direct function of pump flow at eachgiven pump speed.

A further object is to provide regulator mechanism for a pump of thetype specified embodying pump speed sensing means arranged to vary theeffective moment force about the trunnion of the swash plate in apredetermined manner, as the swash plate moves from a zero to a maximumstroke position at any given pump speed,

for establishing a predetermined schedule of pump discharge pressureversus flow at each given speed.

Another object is to provide regulator mechanism for a pump of the typespecified embodying pump speed sensing means arranged to vary theeffective moment force about the trunnion of the swash plate in apredetermined manner at a given position of the swash plate during anincrease in pump speed.

Another object is to provide regulator mechanism for a pump of the typespecified embodying means for controlling or offsetting the effect ofpump plunger inertia irrespective of variations in pump speed or swashplate position.

Another and more specific object is to provide regulator mechanism for apump of the type specified embodying centrifugal weight speed sensingmeans geometrically located with respect to the pivotal axis of theswash plate in such a manner that its effective distance from saidaxisincreases at a rate greater than its radial moment decreases as theswash plate moves from zero to maximum stroke position for increasingdischarge pressure with an increase in flow.

A further object is to provide regulator mechanism for a swash platetype of fuel pump embodying pump speed sensing variable moment of thepumping position of the swash plate and/or pump speed, and means forinterposing a resilient force on the plate tending. to actuate saidplate to maximum stroke position, which force varies in a desiredpreselected manner.

In carrying out the invention, I ofiiset the pivotal mounting of thewobble plate with respect to a center common to the annularlysymmetrically-arranged pump plungers so that the plate of the fluidbeing pumped to move the wobble plate to creases the sensitivity of theplate to changes in plunger or more centrifugal Weights "plate to amaximum stroke position with a force which reaction pressure due tovariations in from an external source, as by changes in throttlesettings. These forces tending to move the swash plate to zero strokeposition are opposed by the action of one tending to tilt the wobblevaries with variations in and by a spring force constant rate or valueplate angle and engine speed, which may have a substantially throughoutthe effective tilt of The resulting control will automatically vary theangle of the wobble plate, and hence delivery pressure, in response tochanges in throttle setting, and may be readily adapted to differentfuel flow requirements.

The foregoing and become apparent in view of the description whichfollows when taken in conjunction with the appended drawings in which:

Figure 1 pump in accordance with the invention;

Figure 2 is a central longitudinal section through they pump of Figure1, only such parts being shown as are necessary to an understanding ofthe invention;

Figures 3 and 4 are curve charts illustrating the operation of the pumpas shown in Figure 2;

Figure 5 is a view in perspective of an assembly which constitutes amodification of the pump control mechanism which is shown in Figure 2;

Figure 6 is another perspective of the assembly of Figmeans arranged toimpose a preselectedforce on the swash plate as a function is unbalancedin a direction. tending to assist the hydraulic reaction on theplungers.

fuel back pressure may have any preselectedv other objects andadvantages will' is a schematic view of a fuel supply system: for a gasturbine engine utilizing a variable displacement me 5 as viewed from thebottom or opposite end of the latter figure, with the wobble plate ofthe pump control mechanism partly broken away;

Figures 7 and 8 are curve chartsillustrating one of the characteristicsobtainable with a. pump when equipped with the unit of Figures 5 and 6;

Figure 9 is a fragmentary view of pump control mechanism whichconstitutes another modification of the mechanism shown in Figure 2; and

Figures 10 and 11. are curve charts illustrating the operation of thecontrol of Figure 9.

It will be understood from the following description that the. springcontrol mechanism shown-in Figures 5 and 6 of the drawings is intendedto be substitutable for the spring control shown in Figures 2 and. 9,said latter spring control being illustrated in simple form so as toavoid unnecessary complexity in the drawings.

Referring to the drawings, and first to Figure 1, a fuel manifold for agas turbine engine is indicated at 10; it has connected thereto aplurality of fuel lines 11 which conduct fuel under pressure to. burnernozzles 12, the latter discharging fuel into the combustion chambers ofthe burner system, not shown. The fuel supply is under manual regulationby means of a fuel control unit 13, which may be of any type suitablefor the function which it is designed to perform. A control unit ofthetype disclosed in my Patent No. 2,689,606, filed December 13, 1946,may be used. In this type of control, the rate of fuel feed isdetermined by the pilot through a control lever 14 which is connected toan all-speed governor throttle valve, not shown, adapted to vary theeifective area of one or more feed restrictions, the fuel head acrossthe said restrictions being automatically varied as a function of enginespeed and changes in entering air density to, among other things,maintain the rate of fuel feed Within predetermined temperature limitsandcompensate for changes in altitude. The fuel is pressurized to theunit by means of an engine driven variable displacement pump, generallyindicated at 15, which receives its fuel from a suitable source ofsupply such as a fuel tank, not shown, by way of conduit16, the fuelbeing discharged under pressure to the control unit by way of conduit17. The member indicated at 18 is a pressure valve which determines themaximum delivery pressure to the nozzles 12, and when such pressure isexceeded, the meteredfuel is by-passed or returned to the supply conduit16 by way of a conduit 19. The unit indicated at 20 is a barometricelement designed to automatically vary the rate of fuel feed as afunction of changes in entering air density; it prevents the fuel-airratio from becoming too rich as altitude is gained and which wouldotherwise result in excessively high burner temperatures andoverspeeding of the engine when operating at high altitudes.

Referring to Figure 2, the pump comprisesa series of plungers 21 whichare symmetrically disposed inannular formation and are mounted toreciprocate in plunger bushings or cylinders 22. The plungers areretracted by means of springs 23, which at their outer ends engageretainers 24 connected to the adjacent ends of the plungers. Eachplunger has mounted'on its outer end a conventional bearing shoe orslipper 25 which is adapted to engage the bearing surface of a cam plate26. The plungers are moved inwardly or towards discharge position bymeans of a wobble or swash plate 27, shown position, which acts on theplate 26 The pump drive shaft is indicated at 29; it is locatedconcentrically of the plungers 21 and has its opposite ends mounted inbearings On the The wobble plate 27 is provided with mounting or hangerbrackets 27', which are secured'on the opposite ends of a trunnion 33,the latter being mounted on the drive shaft 29 in ofiset or eccentricrelation to the longitudinal axis thereof. This offset or eccentricmounting with respect to the annulus or ring described by the plungersunbalances the wobble plate in a direction such that the plungers willexert a moment force on the plate tending to flatten the latter or tiltit to a zero stroke position when the pump is in operation and there isa reaction or back pressure set up by the fluid being pumped. Acentrifugal Weight 34 is also carried by the shaft 29; it is secured ona pin or trunnion 35 which is provided with a hub portion formed with agear 36 in constant mesh with a coacting gear segment 37 formed on theadjacent end of a lever 38, the latter having a hub portion 39 securedon the adjacent end of the trunnion 33.

Fuel from the conduit 16 enters by way of a passage 40 to a chamber 41,from which the fuel is fed through a plurality of passages 42 into theplunger cylinders 22 when the plungers 21 are retracted due to theaction of the springs 23. In each passage 42 is a check valve 43, whichis normally urged to its seat by a spring 44, said valve preventing thefuel from being pressurized to the intake side of the pump.

The ends of the cylinders 22 are each provided with a check valve 45,which is unseated against a spring 46 when the plungers are movedinwardly due to the action of the wobble plate 27. When these valves areunseated on the delivery stroke of the plungers 21, fuel is dischargedto the conduit 17 by way of passages 47 which feed into a common passage48.

In the simplified showing of Figure 2, a spring 50 is disposed to hearat one end against an arm 49 projecting outwardly from the drive shaft29 and at its opposite end against the wobble plate 27. This springtends to tilt the wobble plate toward maximum stroke position; itfunctions to tilt the plate in a stroke-increasing direction when thereaction pressure drops as by an opening movement of the throttle of thefuel control unit 13; it throws the said plate to a full stroke anglewhen the pump or engine is idle, so that when the latter again startsup, there will be no lag in pump delivery; and it also maintains aminimum discharge pressure at low pump or engine speeds which minimumpressure may be sufiicient to compensate for the drop across the control13.

Operation, Figures 1 to 4, inclusive Flow of fuel to the engine isgoverned by the fuel control unit 13. Should the pilot desire toaccelerate, he increases the rate of fuel feed by opening the throttlevalve through manipulation of the control lever 14; at the same time,the fuel head across said valve and consequently the rate of fuel feedmay be varied automatically due to changes in altitude. Any change inthe rate of fuel feed varies the pressure in the passages 47 on thedischarge side of the pump and consequently the back or reactionpressure on the pump plungers 21. Should the pilot accelerate by openingthe throttle, there will be an increase in pressure of the metered fuelto the burner nozzles 12 and a momentary drop in pressure of theunmetered fuel in the passages 47, whereupon the wobble plate 27 tiltsclockwise due to the action of the spring 50 and the centrifugal weight34 and simultaneously, or substantially so, there is an increase inengine speed. As the engine speed increases, the force exerted by thecentrifugal weight 34 also increases; its radius of rotation and hencethe centrifugal force generated increases as the pumping angle of thewobble plate increases. This results in a fuel pressure increase roughlyproportional to engine speed squared times wobble plate angle, and sincespeed times angle constitutes a measure of the rate of fuel feed, thepressure will tend generally to increase proportional to the rate offuel feed times the rpm. In Figure 3, the dotted nozzle requirementcurve represents the schedule of pres sure versus flow required underall engine operating conditions just beyond the control 13 on the way tothe pressure valve 18. Three of the pump speed points on saidrequirement curve illustrate the' required pressure versus matter ofchoice and convenience in flow relation for a condition of maximum fuelconsumption during acceleration at sea level. Less fuel would be used atthese engine speeds during operation, at cruising power or at altitudeor during engine deceleration, as illustrated by two of the 1750 rpm.points, but the fuel flow versus pressure relation, as determined by thenozzles, will still fall along said requirement curve. The straight pumppressure lines represent fuel delivery pressures at three different pumpspeeds as the wobble plate angle, and hence the plunger stroke, goesfrom zero to a maximum. The right-hand terminus of each of these linesrepresents the quantity of fuel delivered at maximum pump stroke andconsequently the maximum fuel available from the pump at the speedindicated. The pressure at each flow point must, of course, lie wellabove the nozzle pressure requirement at the same flow, to absorb acrossthe control unit 13. The difference between the maximum pressure thatthe pump is capable of at any given pump speed and flow and the nozzlepressure requirement at the said flow should equal or exceed the amountof pressure drop the fuel control requires to meet said flowrequirements thru the engine nozzles at said pump speed.

It will be noted that the difference between pump pres sure and nozzlepressure decreases as the flow increases ata fixed rpm. This tends tomake the control regulation stable. The pump pressure lines start from afixed pressure value at zero flow. This is determined by the force ofthe spring 59, the pump plunger areas and the swash plate pivot offset.They then rise at an angle which may be determined by the effect ofspring 50, the weight and radius of the centrifugal weight 34, and bythe effect of plunger inertia.

Figure 4 plots pump discharge pressure against pump speed at maximumplate angle to indicate how the pressure increases as pump or enginespeed increases; and also in relation to discharge nozzle requirementsunder acceleration at maximum air density.

Figures 5 to 11, inclusive To tilt the wobble plate to a full-strokeangle unaided by the action of the centrifugal weight 34, asat a lowspeed or idle condition of the pump obviously requires a spring 50 stilfenough to compressthe plunger springs- 23 on the high or full strokeside of the said plate, and it becomes quite a problem to make a springof substantially constant rate characteristics and yet have thenecessary spring force to perform such function. Furthermore, it may bedesirable to vary the effective thrust or moment force of the wobbleplate spring in a manner such that the force increases as the plate goesto either its low or high plunger stroke position, since by' thisprocedure selected fuel discharge pressure values maybe obtained at anygiven engine or pump speed and/or throttle position. For example, theeffective thrust of the wobble plate spring may progressively oppose theback or reaction pressure of the pump plungers as the angle of' the saidplate increases, or vice versa.

Figures 5 and 6 show a wobble plate spring assembly which may besubstituted for the spring 50 of Figure 2 to obtain the above noted andother advantages. In these figures, parts which correspond to similarparts in Fig ure 2 are given similar reference numerals. Thus the wobbleplate is indicated at 27, the pump drive shaft at 29 and the wobbleplate mounting trunnion or shaft at 33. In place of the single spring 50of Figure 2 there are preferably two springs 50', this'being primarily adesign. The wobble plate 27 has its hanger brackets secured to androtatable with the trunnion or shaft 33. Also secured on the shaft 33are the hubs 51 (one of which is visible in Figure 6) of a pair of arms52 and 52 carrying segmental gears 53 and 54, which are in constant meshwith pinions 55 and 56 (shown as of segmental form) having their hubspinned to a shaft 57. Inwardly of the pinions are a pair of lever arms58 and 59, which have their inner ends pinned to the shaft 57 and theirouter ends pivotally connected to a short shaft 60. The springs 50' aremounted on guide pins 61 and 62, which have their free ends slidinglyprojecting through holes 63 and 64 formed in the shaft and theiropposite ends pivotally anchored on a bearing pin 65 projecting througha bearing lug 66 formed on the pump drive shaft 29. The shaft 57 isrotatabiy mounted in a bearing block 67 shown as clamped on the saiddrive shaft 29, but which in practice could obviously be formed integralwith said shaft.

The entire assembly of Figures 5 and 6, including the wobble plate 27and coating lever arms, gears and springs rotate with the pump driveshaft 29. As this shaft rotates and turns the wobble plate about thesymmetrically arranged pump plungers, the reaction or back pressure ofthe fluid being pumped plus the force of the plunger springs 23 tend totilt the wobble plate counterclockwise (as viewed in Figure 5) about theshaft 33, whereas the thrust of the springs 50 counteract this reactionforce. The effective force of the springs 50 should be sufficient toovercome the force of the plunger springs 23 on the high side of theplate and tilt the latter to a idle, or when the reaction of the fluidbeing pumped is zero. Any tilting movement imparted to the wobble plate27 produces rotation of shaft 33, and this acts through segmental gears53 and 54 to produce a counter-rotation of shaft 57 and a rockingmovement of lever arms 58 and 59. If the wobble plate 27 is tiltedcounterclockwise, or toward zero stroke position, as viewed in Figure 5,it will cause clockwise movement of said lever arms, and vice versa.

Assuming the spring assembly of Figures 5 and 6 is arranged to exert asubstantially constant thrust throughout the effective wobble platerange of tilt, then the lever arms 58 and 59 should lie in a planesubstantially at right angles to the guide pins 61 (the longitudinalthrust axis of springs 50) when maximum stroke position. When the partsare in this position, the springs 50 are in maximum extension while theeffective moment arm of said springs about the shaft 33 is at a maximum.As the wobble plate tilts further in a counterclockwise or plungerstroke decreasing direction, the lever arms 58 and 59 move out of theirninety degree relation to the axial thrust line of the springs 50' insuch a way that as the springs 50' are further compressed the moment armof said springs about shaft 33 decreases to maintain the spring thrustmoment substantially constant.

In this manner, the resistance to movement of the wobbleplate in acounterclockwise or stroke decreasing direction remains substantiallyconstant throughout the range of tilting movement of said plate, andconversely, the spring moment tending to move said plate in a clockwiseor stroke increasing direction remains substantially constant while atthe same time it is sufficient to move the wobble plate to or toward amaximum stroke position when back pressure on the plungers is reduced.Obviously, the levers 58 and 59 may be arranged such that the effectivethrust moment of springs 50 about shaft 33 may be made to eitherincrease or decrease, by any selected amount, as the wobble plate movesfrom its maximum to its zero stroke position, whereby a great variety offuel discharge pressure values may be obtained at any given engine orpump speed and/ or throttle position by variation in design according tothe applicants invention.

A speed sensing weight may be used in Figures 5 and 6 to obtainpredetermined engine speed vs. discharge pressure characteristics suchas described in connection with Figures 1 to 4, inclusive. Thus, byutilizing a centrifugal Weight such as that indicated at 34 in Figure 5,the mechanical moment of the plungers on the wobble plate tending toincrease the pitch of the latter will be assisted by the centrifugalweight as the speed of rotation increases, and as a consequence, a givenchange in back is in a direction tending to the wobble plate is at fulltilt or or reaction pressure at high speeds will proportionally be lesseffective to flatten the plate than at lower speeds.

In Figures 7 and 8, an attempt has been made to illustrate the operatingcharacteristics of a pump when equipped with the assembly of Figures and6 having the weight 34 arranged as shown. Figure 7 plots the resultantof the mechanical moment about the center line of the Wobble platetrunnion '33 (which tends to increase the pitch of said plate) againstplunger stroke at pump speeds of 3500, 1750 and 875 r.p.m., and Figure 8plots this same factor against pump speed at different plunger strokes.The right-hand ordinate in Figures 7 and 8 indicates the hydraulic backpressure tending to decrease the pitch of the wobble plate. A largepercentage of the mechanical moment tending to increase the pitch of thewobble plate at high speeds is the inertia of the reciprocatingplungers, which increases with an increase in the speed of reciprocationand hence pump speed and also, obviously, with the plunger stroke. Thelever arms 58 and 59 and coacting parts graduate or distribute thespring force throughout the range of Wobble plate tilt, whereas thecentrifugal force generated by rotating weight 34' (which tends toincrease the delivered fuel pressure) increases markedly with rpm. andslightly with plate angle.

Instead of having an increase in fuel discharge (plunger stroke) with anincrease in discharge back pressure at a given r.p.m., it may bedesirable to have the opposite eflfect, viz. a decrease in plungerstroke, or wobble plate angle, as the discharge pressure increases. Anexample of where this characteristic may be desirable is in the use oftwo or more pumps in parallel, each having an output capacity sufiicientto supply maximum engine requirements, so that if one pump fails, theother will be able to handle the fuel supply alone. If, in such anarrangement, the pumps have a characteristic as illustrated in Figures 3and 4 or 7 and 8, and if both are running at some intermediate speed,for example 1700 r.p.m., and both are momentarily at an intermediatestroke, if some condition should cause a change in the pressure vs. fiowcharacteristics of one pump, or would throw it out of balance withrespect to the other, its wobble plate would tend to flatten and itsplunger stroke decrease, While at the same time, the other pump would goto full stroke to take care of the fuel supply. In such case, the fuelpressure must increase with decreasing stroke so that under commonpressure both pumps will share the load. However, to improve the life ofthe pump, the pressure is still controlled so as to reduce with speed,and altitude recirculation is avoided. In other Words, at a given speedthe delivery pressure will be maintained substantially constant at allaltitudes. It is therefore desirable that centrifugal compensation beprovided which will vary with r.p.m. but be independent of wobble platepitch or pump stroke; this requires centrifugal force generating meanspositionably variable to overcome the stroke increasing tendency of pumpplunger inertia. In addition, the desired increase in pressure withspeed must be obtained by additional centrifugal force generating meansof substantially constant moment with changes in wobble plate pitch.

Figures and '11 show a delivery characteristic desirable for parallelpumps which may be obtained by modifying the centrifugal speed weightarrangement of Figure 2, as shown in Figure 9 wherein the swash plate isshown in zero stroke position, or by a predetermined balancing of thelever arms 58 and 59 of Figures 5 and 6. For the sake of simplicity,Figure 9 is drawn along the lines of Figure 2, like parts being givencorresponding reference numerals. In addition to the weight 34, there isa weight 68 which functions primarily to oppose the effect of plungerinertia on the wobble plate (which tends to increase the pitch of thewobble plate), whereas the weight 34 tends to increase the resistance ofthe wobble plate to the effect of discharge pressure at high speeds; it

enables discharge pressure to increase with speed. In this arrangement,as the wobble plate angle increases and the centrifugal force generatedby the weight 34 increases, its vector perpendicular to the plane ofrotation decreases in such a manner that its moment at any r.p.m.remains substantially constant. This introduces a component to thewobble plate controlling force which is substantially independent ofplunger stroke and varies generally as the square of the r.p.m. Theweight 68 counteracts the natural tendency of the wobble plate andreciprocating plungers to increase the discharge pressure as the speedsquare times wobble plate angle. When the wobble plate is at a zerostroke position, the weight 68 has maximum centrifugal force, but nomoment. As the Wobble plate angle increases, the radius of Weight 68decreases slightly and its moment vector increases substantially therebyresulting in an effective moment force which tends to flatten the plateand which may exactly counteract or balance pump plunger inertia effector control it in a predetermined manner.

In connection with the above description of Figures 9, l0 and 11, it isapparent that it might be found desirable, in certain pumpingapplications, to utilize the centrifugal weight 34 in pump mechanisms,such as shown in Figures 2 and 5, to obtain different characteristicsthan that obtained with the weight positioned as shown in said figures.Thus, by appropriate variation in the designed position of said weightat maximum wobble plate angle the effective moment arm of said weightmay be varied as the wobble plate moves toward zero stroke position atconstant pump speed, in such a manner that the moment force may act toeither oppose or assist, in varying degree depending on said designposition of the weight, said wobble plate movement. The same variationin the design position of the Weight would result in a like variation inmoment force effect during a change in pump speed.

Substantially the same result may be obtained by arranging the leverarms and gears of the unit of Figures 5 and 6 such that the force of thesprings 50 decreases at maximum plate pitch and increases at neutral orzero pitch. In other words, the effective force of the springs 50'should become greater as the wobble plate moves towards its fiat or zerostroke position. Then, to partially combat plunger inertia, which tendsto increase the pitch of the plate, a suitable weight may be placed onthe ends of the lever arms 58 and 59 or on the shaft 60.

It will be understood that the embodiments of the invention shown anddescribed are primarily for illustrative purposes, and that changes inthe form and relative arrangement of parts may be made to suitrequirements.

I claim:

1. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a plurality ofpistons or plungers, means pivotally mounting said wobble plate on saidshaft in offset or eccentric relation to a center common to the group ofplungers and in a direction to assist the pumping reaction effect on theplungers, and pump regulator means including a centrifugal weightmounted on said shaft and operatively connected to said plate exerting aforce which varies with variations in pump speed and which tends to tiltthe wobble plate progressively towards maximum stroke position withprogressive increases of pump speed during the full speed range ofoperation of the pump.

2. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a plurality ofpistons or plungers, means pivotally mounting said wobble plate on saidshaft in offset or eccentric relation to a center common to the group ofplungers, pump regulator means including a centrifugal weight mounted onsaid shaft and operatively connected to said wobble plate for imposing acentrifugally generated force on the wobble plate during operation .9 ofthe pump, said force varying in'rela'tion' to the tilt of the wobbleplate and in relation to pump speed and applied in a direction tendingto tilt said wobble plate in a stroke increasing direction, andresilient means exerting a mechanical force on the wobble plate in astroke increasing direction.

3. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a series ofannularly disposed pistons or plungers, means pivotally mounting saidwobble plate on said shaft, a centrifugal weight also rnounted on saidshaft adjacent said wobble plate and operatively connected thereto in amanner such as to exert a force on the latter which tends to tilt theplate towards maximum stroke position and which varies in relation tothe speed of the pump, and a spring operatively connected to said wobbleplate which tends to tilt said plate in a stroke increasing direction,said operative connection including variable leverage means fortransmitting the force of said spring to said plate.

4. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a plurality ofannularly disposed pistons or plungers, means pivotally mounting saidwobble plate on said shaft in ofiset or eccentric relation to a centercommon to the group of plungers and in a direction to assist the pumpingreaction effect on the plungers, a speed sensing weight rotatable withsaid shaft mounted adjacent said wobble plate and operatively connectedthereto, and a spring operatively connected to said wobble plate forurging said plate towards maximum stroke position, said latter operativeconnection including means connecting said spring between the shaft andwobble plate in a manner such that the effective spring thrust on saidplate will be maintained substantially constant irrespective ofvariations in the tilt of the plate.

5. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a series ofannularly disposed pistons or plungers, means pivotally mounting saidwobble plate on said shaft, a speed sensing weight rotatable with saidshaft mounted adjacent said wobble plate and operatively connectedthereto for imposing a force on said plate which tends to vary the pitchthereof as a function of pump speed, other means operatively connectedto said wobble plate for modifying the efiect of pump plunger inertia onsaid plate, and resilient means operatively connected to said plate forexerting a tilting force there- 6. A fluid pump having a tiltable wobbleplate carried by a rotatable pump drive shaft and adapted to impartpumping strokes to a series of annularly disposed pistons or plungers,means pivotally mounting said wobble plate on said shaft, meansincluding a centrifugal weight mounted on said shaft for generating acentrifugal force which tends to tilt the wobble plate towards maximumstroke position during operation of the pump, spring means operablyconnected to said wobble plate also tending to tilt said plate towardsmaximum stroke position, and means for generating an additionalcentrifugal force for counteracting the effect of plunger inertia whichtends to increase the pitch of the wobble plate with an increase in pumpspeed.

7. A fluid pump having a tiltable wobble plate carried by a rotatabledrive shaft and adapted to impart pumping strokes to a series ofannularly disposed reciprocable pistons or plungers, a pair ofcentrifugal weights mounted on said shaft adjacent said wobble plate,and means operatively connecting each of said weights to said wobbleplate, one of said weights being arranged to exert a force on said platewhich tends to increase the tilt thereof with an increase in enginespeed, and the other of said weights being arranged to exert a force onsaid plate which modifies he efiect of pump plunger inertia on saidplate.

8. A fluid pump having a tiltable wobble plate" carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a plurality ofpistons or plungers, means pivotally mounting said wobble plate on saidshaft, a centrifugal weight rotatable with said shaft mounted adjacentsaid wobble plate and operatively connected thereto so as to exert avariable force thereon, and, yielding means also operatively connectedto the wobble plate tending to tilt said plate in a stroke increasingdirection, said latter operative connection including leverage means fortransmitting the force of said yielding means to said plate and tomaintain said last named force substantially constant.

9. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a plurality ofpistons or plungers, pump regulator means comprising a centrifugalweight rotatable with the drive shaft mounted adjacent said wobble plateand operably connected thereto, yielding means adapted to move saidwobble plate towards maximum'stroke position, and means operablyconnecting said yielding means between the shaft and wobble plate insuch a manner that the moment force of the yielding means on the saidplate will increasingly oppose movement of said plate towards theminimum pump stroke position thereof.

10. In a fluid pump of the variable displacement type, a tiltablypivoted swash plate, regulator means for controlling the pumpingposition of the swash plate comprising resilient means secured againstaxial movement at one end thereof and operatively connected to the swashplate at the other or axially movable end thereof for imposing asubstantially constant effective torque on said swash plate at allpumping positions thereof, said operative connection including meanseffective to nullify the effect of variations in force output of saidresilient means as said swash plate is actuated from one pumpingposition to another.

11. In a fluid pump of the variable displacement type, a tiltablypivoted swash plate, shaft means for carrying said swash plate, andregulator means for controlling the pumping position of the swash platecomprising a shaft carried by said shaft means on which said plate ispivoted, resilient means secured against axial movement at one endthereof and operatively connected to said pivot shaft and swash plate atthe other or axially movable end thereof, said operative connectionincluding a pivot member also carried by said shaft means, leveragemeans pivoted on said member and abutting and movable with the movableend of said resilient means, and mechanism connecting said member tosaid pivot shaft for transmitting the torque output of said resilientmeans to said swash plate.

12. A fluid pump having a tiltable wobble plate carried by a rotatablepump drive shaft and adapted to impart pumping strokes to a plurality ofannularly disposed pistons or plungers, means pivotally mounting saidwobble plate on said shaft in offset or eccentric relation to a centercommon to the group of plungers and in a direction to assist the pumpingreaction effect on the plungers, a speed sensing means rotatable withsaid shaft and operatively connected to said wobble plate so as to exerta force on the latter tending to tilt the plate towards maximum strokeposition, said force varying as a function of pump speed, resilientmeans operatively connected to said wobble plate also tending to tiltthe wobble plate towards maximum stroke position, said latter operativeconnection including variable leverage means for transmitting the forceoutput of said springs to said plate, and means imposing a centrifugallygenerated force on the wobble plate during operation of the pump, saidlatter means being arranged so that said force tends to counteract theeffects of pump plunger inertia on said plate.

13. A fluid pump having a tiltably pivoted swash plate supported by ashaft and adapted to impart strokes to a series of pistons or plungers,pump control means for producing a resultant mechanical moment about thepivot of the swash plate which varies in such a way that pump dischargepressure varies as a predetermined function of pump flow, said controlmeans including a centrifugal weight mounted on said shaft andoperatively connected to the swash plate and geometrically located withrespect to the pivotal axis of said plate in such a manner that itselfective distance from said axis increases at a rate greater than itsradial moment decreases as the swash plate moves from zero to maximumstroke position, and means operatively connected to the swash plate forcontrolling the effect of pump plunger inertia thereon in apredetermined manner.

14. A fluid pump having a tiltably pivoted wobble plate supported by ashaft means and adapted to impart pumping strokes to a plurality ofpistons or plungers, rotatably mounted pump speed sensing means adjacentsaid wobble plate and operatively connected thereto to impose a variablemoment force on the wobble plate, which force varies as a function ofpump speed and tends to tilt said wobble plate in a maximum strokedirection, and mechanism including resilient means and variable leveragemeans applying a force on the plate which tends to actuate said platetowards maximum stroke position,

the effect of which force is controlled in a predetermined manner bysaid leverage means.

References Cited in the file of this patent UNITED STATES PATENTS962,163 Nichols June 21, 1910 1,521,884 Higgins Jan. 6, 1925 1,820,266Bilderbeck Aug. 25, 1931 2,016,802 Fick Oct. 8, 1935 2,097,436 BennetchNov. 2, 1937 2,115,121 Phillips Apr. 26, 1938 2,165,696 Charter July 11,1939 2,199,081 Perin Apr. 30, 1940 2,225,911 Ingoldby Dec. 24, 19402,232,984 Wahlmark Feb. 25, 1941 2,324,524 Mercier July 20, 19432,389,186 Dodge Nov. 20, 1945 2,579,879 Stoyke et a1. Dec. 25, 19512,737,900 Smith Mar. 13, 1956 FOREIGN PATENTS 592,577 France May 2, 1925605,215 France Feb. 13, 1926

